In a circuit breaker, an off state, a test state, an on state and the like are quite important. When the circuit breaker is in these states, a draw-out functional unit must be locked after being positioned and is not allowed to be drawn out or moved, and cannot be moved from one position to another position, that is, the position must be locked.
While a driving lead screw travels from one of the off, test, and on positions to another position, a locking, unlocking, and lock waiting process is required. China Patent No. CN1402397A discloses a locking device for a draw-out circuit breaker, which provides a device capable of locking under the three different states of off, test, and on. In the patent, this function is achieved through a cooperation of a plurality of members, that is, a fork shaft and an unlocking shaft, a locking sheet and a roller thereon, a slot and a roller slot on a square shaft, and a locking trench on a catching plate.
In the position locking device for the circuit breaker, many members are required to realize position locking and unlocking, and the mutual traveling relation thereof is complicated.